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From: Robert Klemme <shortcutter@googlemail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: How to handle same sanity checks
Date: Sun, 25 Jun 2017 12:31:14 +0200
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On 22.06.2017 11:10, Cecil Westerhof wrote:
> In my code I have several methods that start with:
>      if ((n < MIN_VAL) || (n > MAX_VAL)) {
>          throw new InvalidParameterException(String.format(ERROR_N, n));
>      }
> 
> That is not really DRY.

A few minor remarks: brackets around comparisons are not needed.  Is 
this really part of JCA code?  If not I would just use 
IllegalArgumentException to not give a false impression.

> I could write a method like:
>      private void checkN(n) {
>          if ((n < MIN_VAL) || (n > MAX_VAL)) {
>              throw new InvalidParameterException(String.format(ERROR_N, n));
>          }
>      }
> 
> And then replace all the checks with a call to checkN. But then the
> exception is generated in the method checkN instead of the method that
> has a wrong parameter.
> What is the best way to handle this?

I would not worry about the stack too much (see other subthreads of this 
discussion).  Going through all the hassle of removing an entry just to 
let the stack trace end up one level up is way too much effort here. 
After all, we are talking about a RuntimeException that is intended to 
catch a programmer error, likely during testing.  In that context there 
is usually no issue having logging switched on to a level of verbosity 
to see the stack trace.

I would suggest another name for the method though, more along the lines 
of ensureArgumentIsInRange(final int n).  A "check" can be anything and 
result in anything (ask yourself "what is the result of the check?") but 
what you really want here is that processing only continues if the 
values are within the range.

Kind regards

	robert

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